Sourcemap URL mapping comment should be at the bottom

[Jesse-Box]

Problem

Historically, browsers always look at the bottom of the minified code for the comment.

Acceptance Criteria

Put it at the bottom ;)

[kamilogorek]

It is already the case for DebugID and sourceMappingUrlis generated by 3rd party tools (compilers, transpilers), so we don't control that:

ref:

sentry-cli/src/commands/sourcemaps/inject.rs

Lines 89 to 107 in f8dfc40

	/// Appends the following text to a file:
	/// ```
	///
	/// <CODE_SNIPPET>[<debug_id>]
	/// //# sentryDebugId=<debug_id>
	///```
	/// where `<CODE_SNIPPET>[<debug_id>]`
	/// is `CODE_SNIPPET_TEMPLATE` with `debug_id` substituted for the `__SENTRY_DEBUG_ID__`
	/// placeholder.
	fn fixup_js_file(js_path: &Path, debug_id: Uuid) -> Result<()> {
	let mut js_file = File::options().append(true).open(js_path)?;
	let to_inject =
	CODE_SNIPPET_TEMPLATE.replace(DEBUGID_PLACEHOLDER, &debug_id.hyphenated().to_string());
	writeln!(js_file)?;
	writeln!(js_file, "{to_inject}")?;
	write!(js_file, "{DEBUGID_COMMENT_PREFIX}={debug_id}")?;
	Ok(())
	}

[Jesse-Box]

We found in our testing that wasn't the case

cc: @mitsuhiko

[kamilogorek]

[loewenheim]

The problem is that the comment may be at the bottom when we look at the file, but then we append something else. We should inject our stuff immediately before the comment.

[kamilogorek]

Ohhhhhh, now I get it! #1511