server/errors: add and document error codes

server/szurubooru/facade.py

@@ -11,6 +11,7 @@ from szurubooru import api, middleware
 
 def _map_error(ex, target_class, title):
     return target_class(
+        name=type(ex).__name__,
         title=title,
         description=str(ex),
         extra_fields=getattr(ex, 'extra_fields', {}))
@@ -42,7 +43,11 @@ def _on_processing_error(ex):
 
 def _on_stale_data_error(_ex):
     raise rest.errors.HttpConflict(
-        'Someone else modified this in the meantime. Please try again.')
+        name='IntegrityError',
+        title='Integrity violation',
+        description=(
+            'Someone else modified this in the meantime. '
+            'Please try again.'))
 
 
 def validate_config():

server/szurubooru/func/versions.py

@@ -5,7 +5,7 @@ def verify_version(entity, context, field_name='version'):
     actual_version = context.get_param_as_int(field_name, required=True)
     expected_version = entity.version
     if actual_version != expected_version:
-        raise errors.InvalidParameterError(
+        raise errors.IntegrityError(
             'Someone else modified this in the meantime. ' +
             'Please try again.')
 

server/szurubooru/rest/app.py

@@ -103,6 +103,7 @@ def application(env, start_response):
             '%d %s' % (ex.code, ex.reason),
             [('content-type', 'application/json')])
         blob = {
+            'name': ex.name,
             'title': ex.title,
             'description': ex.description,
         }

server/szurubooru/rest/errors.py

@@ -5,10 +5,15 @@ class BaseHttpError(RuntimeError):
     code = None
     reason = None
 
-    def __init__(self, description, title=None, extra_fields=None):
+    def __init__(self, name, description, title=None, extra_fields=None):
         super().__init__()
+        # error name for programmers
+        self.name = name
+        # error description for humans
         self.description = description
+        # short title for humans
         self.title = title or self.reason
+        # additional fields for programmers
         self.extra_fields = extra_fields