Fix failure locations for panic tests

A failing panic test would produce a failure location pointing to
std.test, instead of one that points to the unit test that defined the
test. This test fixes this by reusing the location the test is defined
on.

Changelog: fixed

std/src/std/test.inko

@@ -539,10 +539,17 @@ class pub Tests {
 
       if code == 101 { return }
 
-      test.failures.push(Failure.new(
-        "the process exited with status {code}",
-        'the process to panic with exit status 101'
-      ))
+      # These tests run in a separate OS process, and `debug.stacktrace` won't
+      # include any frames pointing to the unit tests's source file. To work
+      # around that, we reuse the test's location.
+      let failure = Failure {
+        @got = "the process exited with status {code}",
+        @expected = 'the process to panic with exit status 101',
+        @path = test.path.clone,
+        @line = test.line,
+      }
+
+      test.failures.push(failure)
     }
   }