import_csv: cannot sniff? try default dialects

Author: dale-wahl

datasources/upload/import_csv.py

@@ -78,7 +78,10 @@ def process(self):
         # guess and set the properties as defined in import_formats.py
         infile = temp_file.open("r", encoding=encoding)
         sample = infile.read(1024 * 1024)
-        possible_dialects = [csv.Sniffer().sniff(sample, delimiters=(",", ";", "\t"))]
+        try:
+            possible_dialects = [csv.Sniffer().sniff(sample, delimiters=(",", ";", "\t"))]
+        except csv.Error:
+            possible_dialects = csv.list_dialects()
         if tool_format.get("csv_dialect", {}):
             # Known dialects are defined in import_formats.py
             dialect = csv.Sniffer().sniff(sample, delimiters=(",", ";", "\t"))
@@ -90,7 +93,7 @@ def process(self):
             # With validated csvs, save as is but make sure the raw file is sorted
             infile.seek(0)
             dialect = possible_dialects.pop() # Use the last dialect first
-            self.dataset.log(f"Importing CSV file with dialect: {vars(dialect)}")
+            self.dataset.log(f"Importing CSV file with dialect: {vars(dialect) if type(dialect) == csv.Dialect else dialect}")
             reader = csv.DictReader(infile, dialect=dialect)
 
             if tool_format.get("columns") and not tool_format.get("allow_user_mapping") and set(reader.fieldnames) & \