From f83d1a840e0a9b23737c31191ca46d6277cf9569 Mon Sep 17 00:00:00 2001
From: Yuya Nishihara <yuya@tcha.org>
Date: Thu, 21 Mar 2024 00:40:02 +0900
Subject: [PATCH] templater: don't panic on PropertyPlaceholder unset error

The idea is that, if .extract() succeeded in static context, it means the
property can be evaluated as constant. This will potentially eliminate
expect_string_literal_with(), though I'm not too sure if it's a good idea.
If needed, maybe we can extend the idea to suppress type/name resolution errors
by "if(some_static_config_knob, x, y)".
---
 cli/src/templater.rs | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/cli/src/templater.rs b/cli/src/templater.rs
index 4aa2f9291..c588d0bf8 100644
--- a/cli/src/templater.rs
+++ b/cli/src/templater.rs
@@ -620,12 +620,11 @@ impl<O: Clone> TemplateProperty for PropertyPlaceholder<O> {
     type Output = O;
 
     fn extract(&self) -> Result<Self::Output, TemplatePropertyError> {
-        Ok(self
-            .value
-            .borrow()
-            .as_ref()
-            .expect("placeholder value must be set before evaluating template")
-            .clone())
+        if let Some(value) = self.value.borrow().as_ref() {
+            Ok(value.clone())
+        } else {
+            Err(TemplatePropertyError("Placeholder value is not set".into()))
+        }
     }
 }