Update file_handler.py

Added error/exception handling and better file handling

data/contexts/file_handler.py

@@ -1,17 +1,36 @@
-import os
-
 def read_files(file_list):
     contents = []
     for filename in file_list:
-        f = open(filename, 'r')
-        data = f.read()
-        contents.append(data)
+        f = None
+        try:
+            f = open(filename, 'r', encoding='utf-8')
+            contents.append(f.read())
+        except Exception as e:
+            print(f"Error reading {filename}: {e}")
+            contents.append(None)
+        finally:
+            if f:
+                f.close()
     return contents
 
 def write_output(data, filename):
-    with open(filename, 'w') as f:
+    f = None
+    try:
+        f = open(filename, 'w', encoding='utf-8')
         f.write(data)
+    except Exception as e:
+        print(f"Error writing to {filename}: {e}")
+    finally:
+        if f:
+            f.close()
 
 def append_to_file(filename, data):
-    with open(filename, 'a') as f:
-        f.write(data)
+    f = None
+    try:
+        f = open(filename, 'a', encoding='utf-8')
+        f.write(data)
+    except Exception as e:
+        print(f"Error appending to {filename}: {e}")
+    finally:
+        if f:
+            f.close()