MAINT: Put all dtype checks into one condition.

src/caosadvancedtools/table_importer.py

@@ -338,11 +338,11 @@ class TableImporter():
             # float, because CaosDB does not have different sizes anyway.
             col_dtype = df.dtypes[key]
             if not strict and not np.issubdtype(col_dtype, datatype):
-                issub = np.issubdtype
                 #  These special cases should be fine.
-                if issub(col_dtype, np.integer) and issub(datatype, np.floating):
-                    df[key] = df[key].astype(datatype)
-                elif datatype == str:
+                if ((datatype == str)
+                        or (np.issubdtype(col_dtype, np.integer)
+                            and np.issubdtype(datatype, np.floating))
+                    ):
                     df[key] = df[key].astype(datatype)
 
             # Now check each element