Extend hint for unknown variables in math (#5038)

crates/typst/src/foundations/scope.rs

@@ -137,6 +137,17 @@ fn unknown_variable_math(var: &str, in_global: bool) -> HintedString {
         res.hint(eco_format!(
             "`{var}` is not available directly in math, try adding a hash before it: `#{var}`",
         ));
+    } else {
+        res.hint(eco_format!(
+            "if you meant to display multiple letters as is, try adding spaces between each letter: `{}`",
+            var.chars()
+                .flat_map(|c| [' ', c])
+                .skip(1)
+                .collect::<EcoString>()
+        ));
+        res.hint(eco_format!(
+            "or if you meant to display this as text, try placing it in quotes: `\"{var}\"`"
+        ));
     }
 
     res

tests/suite/math/call.typ

@@ -81,6 +81,12 @@ $
   bx(x y)  &&quad  bx(x (y z))  &quad  bx(x y^z) \
 $
 
+--- math-call-unknown-var-hint ---
+// Error: 4-6 unknown variable: ab
+// Hint: 4-6 if you meant to display multiple letters as is, try adding spaces between each letter: `a b`
+// Hint: 4-6 or if you meant to display this as text, try placing it in quotes: `"ab"`
+$ 5ab $
+
 --- issue-3774-math-call-empty-2d-args ---
 $ mat(;,) $
 // Add some whitespace/trivia: