Clean up warnings printed when rr.init hasn't been called (#2209)

The recording handle work changed the behavior of some of our warnings
when calling a log API without having called `rr.init`.

Before:
```
[2023-05-25T09:09:33Z WARN  re_sdk::global] There is no currently active Data recording available for the current thread (ThreadId(1)): have you called `set_global()` and/or `set_thread_local()` first?
WARNING:rerun:Rerun is disabled - log_text_box() call ignored
```

After:
```
WARNING:rerun:Rerun is disabled - log_text_box() call ignored. You must call rerun.init before using log APIs.
```

PR Build Summary: https://build.rerun.io/pr/2209

crates/re_sdk/src/global.rs

@@ -65,6 +65,33 @@ impl RecordingStream {
         rec
     }
 
+    // Internal implementation of `get()` that doesn't print a warning if no recording is found.
+    // Used from python-bridge.
+    #[inline]
+    #[doc(hidden)]
+    pub fn get_quiet(
+        which: RecordingType,
+        overrides: Option<RecordingStream>,
+    ) -> Option<RecordingStream> {
+        let rec = overrides.or_else(|| {
+            Self::get_any(RecordingScope::ThreadLocal, which)
+                .or_else(|| Self::get_any(RecordingScope::Global, which))
+        });
+
+        if rec.is_none() {
+            // NOTE: This is the one and only place where a warning about missing active recording
+            // should be printed, don't stutter!
+            re_log::debug_once!(
+                "There is no currently active {which} recording available \
+                for the current thread ({:?}): have you called `set_global()` and/or \
+                `set_thread_local()` first?",
+                std::thread::current().id(),
+            );
+        }
+
+        rec
+    }
+
     // --- Global ---
 
     /// Returns the currently active recording of the specified type in the global scope, if any.

rerun_py/rerun_sdk/rerun/__init__.py

@@ -366,7 +366,10 @@ def start_web_viewer_server(port: int = 0) -> None:
     """
 
     if not bindings.is_enabled():
-        logging.warning("Rerun is disabled - self_host_assets() call ignored")
+        logging.warning(
+            "Rerun is disabled - start_web_viewer_server() call ignored. You must call rerun.init before starting the"
+            + " web viewer server."
+        )
         return
 
     bindings.start_web_viewer_server(port)

rerun_py/rerun_sdk/rerun/log/log_decorator.py

@@ -32,7 +32,9 @@ def wrapper(*args: Any, **kwargs: Any) -> Any:
         recording = RecordingStream.to_native(kwargs.get("recording"))
         if not bindings.is_enabled(recording):
             # NOTE: use `warnings` which handles runtime deduplication.
-            warnings.warn(f"Rerun is disabled - {func.__name__}() call ignored")
+            warnings.warn(
+                f"Rerun is disabled - {func.__name__}() call ignored. You must call rerun.init before using log APIs."
+            )
             return
 
         if rerun.strict_mode():

rerun_py/rerun_sdk/rerun/sinks.py

@@ -50,7 +50,7 @@ def save(path: str, recording: Optional[RecordingStream] = None) -> None:
     """
 
     if not bindings.is_enabled():
-        logging.warning("Rerun is disabled - save() call ignored")
+        logging.warning("Rerun is disabled - save() call ignored. You must call rerun.init before saving a recording.")
         return
 
     recording = RecordingStream.to_native(recording)

rerun_py/src/python_bridge.rs

@@ -274,7 +274,7 @@ fn get_recording_id(recording: Option<&PyRecordingStream>) -> Option<String> {
 /// specified recording otherwise, if any.
 #[pyfunction]
 fn get_data_recording(recording: Option<&PyRecordingStream>) -> Option<PyRecordingStream> {
-    RecordingStream::get(
+    RecordingStream::get_quiet(
         rerun::RecordingType::Data,
         recording.map(|rec| rec.0.clone()),
     )
@@ -345,7 +345,7 @@ fn set_thread_local_data_recording(
 /// specified recording otherwise, if any.
 #[pyfunction]
 fn get_blueprint_recording(overrides: Option<&PyRecordingStream>) -> Option<PyRecordingStream> {
-    RecordingStream::get(
+    RecordingStream::get_quiet(
         rerun::RecordingType::Blueprint,
         overrides.map(|rec| rec.0.clone()),
     )