errors for empyt and misssing file on publish

lbry/error/README.md

@@ -36,6 +36,8 @@ Code | Name | Message
 112 | InputValueIsNone | None or null is not valid value for argument '{argument}'.
 113 | ConflictingInputValue | Only '{first_argument}' or '{second_argument}' is allowed, not both.
 114 | InputStringIsBlank | {argument} cannot be blank.
+115 | EmptyPublishedFile | Cannot publish empty file: {file_path}
+116 | MissingPublishedFile | File does not exist: {file_path}
 **2xx** | Configuration | Configuration errors.
 201 | ConfigWrite | Cannot write configuration file '{path}'. -- When writing the default config fails on startup, such as due to permission issues.
 202 | ConfigRead | Cannot find provided configuration file '{path}'. -- Can't open the config file user provided via command line args.

lbry/error/__init__.py

@@ -91,6 +91,20 @@ class InputStringIsBlankError(InputValueError):
         super().__init__(f"{argument} cannot be blank.")
 
 
+class EmptyPublishedFileError(InputValueError):
+
+    def __init__(self, file_path):
+        self.file_path = file_path
+        super().__init__(f"Cannot publish empty file: {file_path}")
+
+
+class MissingPublishedFileError(InputValueError):
+
+    def __init__(self, file_path):
+        self.file_path = file_path
+        super().__init__(f"File does not exist: {file_path}")
+
+
 class ConfigurationError(BaseError):
     """
     Configuration errors.

lbry/schema/attrs.py

@@ -10,6 +10,7 @@ from google.protobuf.json_format import MessageToDict
 
 from lbry.crypto.base58 import Base58
 from lbry.constants import COIN
+from lbry.error import MissingPublishedFileError, EmptyPublishedFileError
 
 from lbry.schema.mime_types import guess_media_type
 from lbry.schema.base import Metadata, BaseMessageList
@@ -139,10 +140,10 @@ class Source(Metadata):
             self.name = os.path.basename(file_path)
             self.media_type, stream_type = guess_media_type(file_path)
             if not os.path.isfile(file_path):
-                raise Exception(f"File does not exist: {file_path}")
+                raise MissingPublishedFileError(file_path)
             self.size = os.path.getsize(file_path)
             if self.size == 0:
-                raise Exception(f"Cannot publish empty file: {file_path}")
+                raise EmptyPublishedFileError(file_path)
             self.file_hash_bytes = calculate_sha384_file_hash(file_path)
             return stream_type