Return fewer NULLs in parsing

src/parse.c

@@ -88,7 +88,7 @@ struct ucl_object *ucl_token_next(const char **curr_src) {
 
     // Unreachable
     assert(false);
-    return NULL;
+    return ucl_error_create("Unreachable error in ucl_token_next");
 }
 
 struct ucl_object *ucl_tokenize(const char *source) {
@@ -129,6 +129,9 @@ struct ucl_object *ucl_parse_token_atom(struct ucl_object *maybe_atom) {
         case UCL_TYPE_COUNT:
             assert(false);
     }
+    if (atom == NULL) {
+        return ucl_error_create("Unreachable error in ucl_parse_token_atom");
+    }
     return atom;
 }
 
@@ -178,11 +181,6 @@ static struct ucl_object *ucl_parse_tokens_recursive(struct ucl_object **token_i
 
             next_sexp = ucl_parse_tokens_recursive(token_iter);
             UCL_RET_IF_ERROR(next_sexp);
-            if (next_sexp == NULL) {
-                // Error somewhere in the recursive parsing
-                ucl_object_delete(list);
-                return NULL;
-            }
 
             *next_node = ucl_cell_create(next_sexp, NULL);
             next_node = &(*next_node)->cell.cdr;
@@ -192,7 +190,7 @@ static struct ucl_object *ucl_parse_tokens_recursive(struct ucl_object **token_i
     }
     // Any other symbol type should have been an atom, this shouldn't happen
     assert(false);
-    return ucl_error_create("Unreachable parse error");
+    return ucl_error_create("Unreachable ucl_parse_tokens_recursive error");
 }
 
 // parse_tokens -> doesn't care about quotes, terminates on EOF
@@ -218,8 +216,6 @@ struct ucl_object *ucl_parse_tokens(struct ucl_object *tokens) {
     }
 
     return resultl;
-  error:
-    return NULL;
 }
 
 // TODO: Should the parse a single sexp (return the last-parsed position), or