Improve SQLPage function argument warnings (#1225)

* improve sqlpage function argument warnings with source context

Made-with: Cursor

* Param extraction: Result-based errors, single caller message, no CompoundIdentifier special case

- expr_to_stmt_param returns Result<StmtParam, ExprToParamError>; error carries only line + kind (UnsupportedExpr, UnemulatedFunction, NamedArgs)
- function_args_to_stmt_params logs one formatted message (ctx.format_param_error) then returns Err
- Single unsupported-expr arm; expr_summary() used for description
- Rename ParamWarnContext to ParamExtractContext

Made-with: Cursor

* Surface param extraction error in parse result; add parse_sql error-message tests; remove are_params_extractable

- When func_call_to_param returns StmtParam::Error, store it and have extract_parameters return Err so parse yields ParsedStatement::Error with specialized message
- Add test_parse_sql_unsupported_expr_in_sqlpage_arg and test_parse_sql_unemulated_function_in_sqlpage_arg
- Remove dead are_params_extractable and its unused import

Made-with: Cursor

* Refactor sqlpage function argument error messages to match user expectations

- Overhauled ExprToParamError formatting to construct exact user-friendly descriptions.
- Removed superfluous anyhow::Context prefixes in func_call_to_param.
- Passed source_path properly through validate_function_calls to ensure file line numbers populate the new error template accurately.
- Renamed error test file to match its dynamic error output signature.
- Removed redundant mut mutability warnings on parsing logic loops.

* improve error messages

* Refactor SqlPageFunctionError representation to clean up 'syntax error' wrappers

- Replaced stringly-typed anyhow errors with a strongly typed SqlPageFunctionError.
- Removed source_path threading completely from the parameter extraction phases, conforming to better separation of concerns.
- Appended file path prefix dynamically at the evaluation stage in clone_anyhow_err strictly when downcasting to SqlPageFunctionError.
- Removed the confusing generic 'Caused by: x.sql contains a syntax error...' wrapper from actual function logic errors.

* Remove redundant 'reorganize' hint from error message

* readd deleted test

* split parameter extraction logic into a separate file

* Add to changelog

Author: lovasoa

CHANGELOG.md

@@ -4,6 +4,7 @@
  - OIDC protected and public paths now respect the site prefix when it is defined.
  - Fix: forms without submit or reset buttons no longer keep extra bottom spacing.
  - add submit and reset form button icons: validate_icon, reset_icon, reset_color
+ - improve error messages when sqlpage functions are used incorrectly. Include precise file reference and line number
 
 ## 0.42.0 (2026-01-17)
 

src/webserver/database/execute_queries.rs

@@ -331,6 +331,16 @@ fn debug_row(r: &AnyRow) {
 }
 
 fn clone_anyhow_err(source_file: &Path, err: &anyhow::Error) -> anyhow::Error {
+    if let Some(func_err) = err.downcast_ref::<super::sql::SqlPageFunctionError>() {
+        let line = func_err.line;
+        let loc = if line > 0 {
+            format!(":{line}")
+        } else {
+            String::new()
+        };
+        return anyhow::anyhow!("{}{loc} {}", source_file.display(), func_err);
+    }
+
     let mut e = anyhow!("{} contains a syntax error preventing SQLPage from parsing and preparing its SQL statements.", source_file.display());
     for c in err.chain().rev() {
         e = e.context(c.to_string());