Better error message.

tools/cmake2meson.py

@@ -135,5 +135,8 @@ if __name__ == '__main__':
     if len(sys.argv) != 2:
         print(sys.argv[0], '<CMake project root>')
         sys.exit(1)
-    convert(sys.argv[1])
-
+    try:
+        convert(sys.argv[1])
+    except Exception as e:
+        print('Error:', e)
+        sys.exit(1)