executor: Improve FunctionExecution error messages.

core/executor/src/error.rs

@@ -81,8 +81,8 @@ pub enum Error {
 	#[display(fmt="Requested allocation size is too large")]
 	RequestedAllocationTooLarge,
 	/// Execution of a host function failed.
-	#[display(fmt="Function execution failed with: {}", _0)]
-	FunctionExecution(String),
+	#[display(fmt="Host function {} execution failed with: {}", _0, _1)]
+	FunctionExecution(String, String),
 }
 
 impl std::error::Error for Error {

core/executor/src/wasmi_execution.rs

@@ -309,7 +309,7 @@ impl wasmi::Externals for FunctionExecutor {
 		)?;
 
 		function.execute(self, &mut args)
-			.map_err(Error::FunctionExecution)
+			.map_err(|msg| Error::FunctionExecution(function.name().to_string(), msg))
 			.map_err(wasmi::Trap::from)
 			.map(|v| v.map(Into::into))
 	}

core/executor/src/wasmtime/function_executor.rs

@@ -184,7 +184,7 @@ impl<'a> SandboxCapabilities for FunctionExecutor<'a> {
 				values_vec.as_mut_ptr() as *mut u8,
 			)
 		} {
-			return Err(Error::FunctionExecution(message));
+			return Err(Error::Other(message));
 		}
 
 		// Load the return value out of `values_vec`.

core/executor/src/wasmtime/trampoline.rs

@@ -110,9 +110,7 @@ unsafe fn stub_fn_inner(
 
 	// Execute and write output back to the stack.
 	let return_val = func.execute(&mut context, &mut args)
-		.map_err(|e| Error::FunctionExecution(
-			format!("error in external function {}: {}", func.name(), e)
-		))?;
+		.map_err(|e| Error::FunctionExecution(func.name().to_string(), e))?;
 	if let Some(val) = return_val {
 		write_value_to(values_vec, val);
 	}