Non default build folder.

If build folder is other than "builddir", "Could not fetch targets. See Meson Build output tab for more info." information is shown while a mason task is run. The "Mason Build" output shows "false" only, instead of an information about the issue.

Reproduce the Mason task with a build folder other than "builddir" and inspect the Mason Build output and target-fetching task path. Trace why the output is only "false" and make the failure show useful information about the issue; verify the original error is replaced with actionable output.

Written by the indexing model from the issue text.