Some very minor improvement in one error handling and one warning mes…

…sage. (#1686)

1. Do not throw error if `clear_instrumentation_reports()` does not have
anything to clear. (The function is useful to avoid accumulating many,
many obsolete profile data files over time)
2. Put some more information in a warning message.

dace/sdfg/sdfg.py

@@ -949,7 +949,11 @@ def clear_instrumentation_reports(self):
         Clears the instrumentation report folder of this SDFG.
         """
         path = os.path.join(self.build_folder, 'perf')
-        for fname in os.listdir(path):
+        try:
+            files = os.listdir(path)
+        except FileNotFoundError:
+            return
+        for fname in files:
             if not fname.startswith('report-'):
                 continue
             os.unlink(os.path.join(path, fname))
@@ -2288,8 +2292,8 @@ def compile(self, output_file=None, validate=True) -> 'CompiledSDFG':
                 sdfg.name = f'{self.name}_{index}'
                 index += 1
             if self.name != sdfg.name:
-                warnings.warn('SDFG "%s" is already loaded by another object, '
-                              'recompiling under a different name.' % self.name)
+                warnings.warn(f"SDFG '{self.name}' is already loaded by another object, recompiling under a different "
+                              f"name '{sdfg.name}'.")
 
             try:
                 # Fill in scope entry/exit connectors