When a source-map has an inline source, any source-map linked from
that source should only be loaded if itself is also inline; it should not
attempt to load a source-map from the file-system. Otherwise we can
find ourselves with inadvertent infinite cyclic dependencies.
For example, if a transpiler takes a file (e.g. index.js) and generates
a new file overwriting the original file - capturing the original
source inline in the new source-map (index.js.map) - the source
file loader might read the inline original file (also index.js) and
then try to load the `index.js.map` file from disk - ad infinitum.
Note that the first call to `loadSourceFile()` is special, since you can
pass in the source-file and source-map contents directly as in-memory
strrngs. This is common if the transpiler has just generated these and has
not yet written them to disk.
When the contents are passed into `loadSourceFile()` directly, they are
not treated as "inline" for the purposes described above since there is
no chance of these "in-memory" source and source-map contents being caught
up in a cyclic dependency.
Fixes#40408
PR Close#40435
dc06873c72