theme: continue execution after failure for one theme (#50)

src/caelestia/utils/logging.py

@@ -0,0 +1,20 @@
+from time import strftime
+
+
+def log_message(message: str) -> None:
+    timestamp = strftime("%Y-%m-%d %H:%M:%S")
+    print(f"[{timestamp}] {message}")
+
+
+def log_exception(func):
+    """Log exceptions to stdout instead of raising
+
+    Used by the `apply_()` functions so that an exception, when applying
+    a theme, does not prevent the other themes from being applied.
+    """
+    def wrapper(*args, **kwargs):
+        try:
+            func(*args, **kwargs)
+        except Exception as e:
+            log_message(f'Error during execution of "{func.__name__}()": {str(e)}')
+    return wrapper