bun run: print the package.json parse error instead of "Script not found" by robobun · Pull Request #41700 · oven-sh/bun

robobun · 2026-09-06T17:01:47Z

Problem

When the project's package.json does not parse, bun run <script> prints only error: Script not found "<script>" and exits 1. The parse error that bun -e, bun build, and bun install print for the same file never appears. npm run prints EJSONPARSE and names the file.
The cause is the not-found exit in Run::exec (src/runtime/cli/run_command.rs:2661). The resolver records the parse error in ctx.log and returns a DirInfo with no package_json. The script lookup sees no scripts and prints "Script not found" without that log.

Fix

On the not-found exit, print ctx.log to stderr when it holds errors. This is the same dump configure_env_for_run and boot_failed_exit already use in this file.
When no package.json loaded at all (enclosing_package_json is None) and the log explains why, skip "Script not found". The parse error is the message. A missing script in a file that did not load is not a fact bun can report.
When a package.json did load (for example the project's own file is valid and an ancestor's is broken), "Script not found" is still printed after the log. The script really is absent from the file bun used.
Verified: test/cli/run/run_command.test.ts (two new tests, stock bun fails both). Also ran test/cli/run/if-present.test.ts.

Background

Run::exec calls configure_env_for_run, which asks the resolver for the cwd DirInfo. The resolver walks up the directory tree and parses each package.json it finds. A parse failure goes to the resolver's log (PackageJSON::parse in src/resolver/package_json.rs:461) and the directory is treated as having no package.json.
ctx.log is the process-lifetime bun_ast::Log that the resolver writes to. Other exits in run_command.rs print it before their own error line. The not-found exit did not.

Notes

Reproduction with stock bun (1.4.3):

printf '{"name": "p", "scripts": {"s": "echo hi"' > package.json
bun run s      # error: Script not found "s"
bun -e '1'     # error: Expected "}" but found end of file, at package.json:1:40

With this change, bun run s prints the parse error with the file path and line:column, and exits 1.

bun run ./missing.js with the same broken package.json prints the parse error and then Module not found "./missing.js". That message is about the file argument, so it stays.

Not covered here: a package.json that is a directory. The resolver only parses regular files, so nothing is logged and the output stays Script not found. Also not covered: bun build failing on a broken ancestor package.json when the project's own file is valid. That is a resolver-level decision about ancestor manifests and is separate from this exit path.

no test proof · iteration 0 · platform-specific test(s) that do not run on this machine, deferring to CI, which covers all platforms: test/cli/run/run_command.test.ts

…und" The resolver records a package.json that fails to parse in the log and returns a DirInfo without it. The script lookup then reported "Script not found" and never printed that log. Print the log on the not-found exit. When no package.json loaded at all, the parse error is the message and "Script not found" is not printed.

robobun · 2026-09-06T17:01:53Z

Status: reproduced with stock bun 1.4.3 (printf '{"name": "p", "scripts": {"s": "echo hi"' > package.json && bun run s prints only Script not found). The fix prints the parse error on the not-found exit. Tests in test/cli/run/run_command.test.ts fail on stock bun and pass with this branch.

coderabbitai · 2026-09-06T17:01:54Z

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src/runtime/cli/run_command.rs
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robobun · 2026-09-06T17:02:04Z

^{Updated 1:24 PM PT - Sep 6th, 2026}

❌ @robobun, your commit ab202f1 has 2 failures in Build #111521 (All Failures):

🧪 To try this PR locally:

bunx bun-pr 41700

That installs a local version of the PR into your bun-41700 executable, so you can run:

bun-41700 --bun

claude

Nothing blocking. The comments below are optional suggestions. There is no need to push a fix for them before merging.

claude · 2026-09-06T17:16:04Z

                        bstr::BStr::new(target_name),
                    );
-                } else {
+                } else if !(has_log_errors && root_dir.enclosing_package_json.is_none()) {


🟡 (optional) The suppression key is the inherited enclosing_package_json, so the misleading "Script not found" line this PR removes still prints in the common monorepo/workspace case: cwd's own package.json fails to parse, an ancestor's is valid, enclosing_package_json is Some(ancestor), and the user sees the parse error followed by "Script not found" for a script that may well be defined in the file that did not load. Fix: gate suppression on the cwd file being the one that failed (e.g. root_dir.package_json.is_none() when a package.json exists in cwd), not on whether any ancestor loaded.

Extended reasoning...

DirInfo.enclosing_package_json is inherited from the parent chain (src/resolver/resolver.rs:6231-6233) and only overwritten with the directory's own file when that file parses (resolver.rs:6354-6361). In a workspace: /repo/package.json valid, /repo/pkgs/app/package.json malformed, cwd /repo/pkgs/app, bun run dev. The resolver logs the parse error and leaves root_dir.package_json = None, but root_dir.enclosing_package_json = Some(/repo/package.json). At line 2704 has_log_errors && root_dir.enclosing_package_json.is_none() is true && false, so the guard is false and Script not found "dev" prints after the parse error. Base branch printed only Script not found, so this path is strictly better than base — but it is exactly the "missing script in a file that did not load" case the PR description says should show only the parse error, and workspaces (where every package sits under a valid root package.json) are where a broken subdirectory package.json is most likely. The second new test only exercises the reverse layout (cwd valid, ancestor broken), so this…

Verification: nit — the mechanism is exactly as described, but merging leaves the base strictly better on this path too (base showed only "Script not found" with no parse error at all; this PR adds the parse error and merely fails to also suppress the trailing line in the monorepo-leaf case). Mechanism verified: - src/resolver/resolver.rs:6231-6233: `info.enclosing_package_json =… | nit — the mechanism is…

claude · 2026-09-06T17:16:04Z

+            let log = unsafe { ctx.log() };
+            let has_log_errors = log.has_errors();
+            if has_log_errors {
+                let _ = log.print(std::ptr::from_mut::<bun_core::io::Writer>(
+                    Output::error_writer(),
+                ));
+            }


🟣 Pre-existing sibling left unfixed: the new ctx.log() dump is placed after the --if-present early return at line 2658, so bun run --if-present <script> with a broken package.json still exits 0 with no output — the parse error stays swallowed exactly as on the base branch. Fix: dump ctx.log() before the if_present check (or inside it) so every not-found exit surfaces the resolver's package.json error, whether or not --if-present suppresses the "Script not found" line and the nonzero exit.

Extended reasoning...

Run::exec reaches the failure section: line 2657 checks ctx.runtime_options.if_present and returns Ok(true) before line 2668 reads ctx.log(). With printf '{"scripts":{"s":"x"' > package.json && bun run --if-present s, the resolver logs the parse error into ctx.log and returns a DirInfo with enclosing_package_json = None; no script matches; if_present returns success and the process exits 0 with empty stderr. On base this path also swallowed the error, so this is a same-class exit the partial fix leaves behind — the PR's stated goal ("print the package.json parse error") does not reach --if-present users, who are the ones most likely to miss that their scripts silently stopped running. Hoisting the let log = …; if log.has_errors() { log.print(...) } block above line 2657 covers both exits with no behavior change for the tested paths.

Verification: pre-existing — same-class sibling exit left uncovered by the fix. At src/runtime/cli/run_command.rs:2657-2659: if ctx.runtime_options.if_present { return Ok(true); } returns before the newly added log dump at 2668-2674 (let log = unsafe { ctx.log() }; ... log.print(...)). The failure scenario is exactly as stated: with a malformed package.json, the resolver records the parse…

robobun · 2026-09-17T03:31:48Z

This also fixes #42992, which reports the same "Script not found" output for a package.json that does not parse.

github-actions Bot added the claude label Sep 6, 2026

claude Bot reviewed Sep 6, 2026

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robobun mentioned this pull request Sep 17, 2026

bun run <script> prints "Script not found" and hides the error when package.json does not parse #42992

Closed

This was referenced Oct 13, 2026

run: report a package.json that does not parse instead of using a parent's scripts #45113

Open

json: require end of input after the root value at every parser entry #45386

Draft

Jarred-Sumner mentioned this pull request Oct 19, 2026

CLI: fixes for bun run, flags, bunfig.toml, .env, --filter, bun init and completions #46007

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bun run: print the package.json parse error instead of "Script not found" - #41700

bun run: print the package.json parse error instead of "Script not found"#41700
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