First attempt at fixing by reading all indirect references containing a reference to a single value as the original value is a failure. Turns out the @size helper treats numeric types in indirect references differently.

js/test_cases/helpers_size/main.dust

@@ -1,3 +1,10 @@
 The size of val ({val|js|s}) is {@size key=val /}{~n}
 The size of "{~lb}val{~rb}" is {@size key="{val}" /}{~n}
+{#val foo="{val}"}
+    The size of foo ({foo|js|s}) is {@size key=foo /}{~n}
+    The size of "{~lb}foo{~rb}" is {@size key="{foo}" /}{~n}
+{:else}
+    The size of foo ({foo|js|s}) is {@size key=foo /}{~n}
+    The size of "{~lb}foo{~rb}" is {@size key="{foo}" /}{~n}
+{/val}
 The size with no key is {@size /}{~n}