npm run start throws: Error: invalid type: sequence, expected a string at line 5 column 11

[haai]

🐛 Bug description

I am try to compile the webpack wasm-pack project and then I get an Rust-Compilation Error:

✅  Your crate has been correctly compiled

10% building 0/3 entries 3/3 dependencies 0/3 modulesError: invalid type: sequence, expected a string at line 5 column 11
Caused by: invalid type: sequence, expected a string at line 5 column 11

But there is no good information where this error is coming from.
Do you know a way how to tackle this down?

Guess there is an issue with wasm-bindgen?

🤔 Expected Behavior

Compilation successful.
wasm-pack build works fine.

👟 Steps to reproduce

unkown .. just run "npm run start".

🌍 Your environment

wasm-pack 0.13.0

[kpreid]

I am seeing the same cryptic error, but with different circumstances and timing, and not using npm at all:

$ wasm-pack build --target web --out-dir <path> --dev <path>
[INFO]: 🎯  Checking for the Wasm target...
[INFO]: 🌀  Compiling to Wasm...
    Blocking waiting for file lock on package cache
    Finished `dev` profile [optimized + debuginfo] target(s) in 0.08s
Error: invalid type: sequence, expected a string at line 4 column 19
Caused by: invalid type: sequence, expected a string at line 4 column 19

It occurs randomly, in that if I rerun the same command it will succeed. This is with wasm-pack 0.13.1.