Fix JS VM's handling of single-body block function with a header

2 files changed, 2 insertions, 1 deletions

diff --git a/docs/bqn.js b/docs/bqn.js
index 1314e40c..bfa87f34 100644
--- a/docs/bqn.js
+++ b/docs/bqn.js
@@ -134,10 +134,10 @@ let run = (B,O,F,S,L,T,src,env) => { // Bytecode, Objects, Blocks, Bodies, Locat
     let c,vid,def;
     if (isnum(ind)) {
       [c,vid] = gen(ind);
+      c="do {"+c+"} while (0);\nthrow Error('No matching case');\n";
       if (useenv) { c =          "const e=env;"+c; env.vid=vid; }
       else if (imm) c =          "const e=[...e2];e.vid=vid;e.p=oe;"+c;
       else c = "const fn=(x, w)=>{const e=[...e2];e.vid=vid;e.p=oe;e[0]=fn;e[1]=x;e[2]=w;"+c+"};"+repdf[type]+"return fn;";
-      c="do {"+c+"} while (0);\nthrow Error('No matching case');\n";
       def = useenv ? "env" : ("new Array("+vid.length+").fill(null)");
     } else {
       if (imm !== +(ind.length<2)) throw "Internal error: malformed block info";
diff --git a/test/cases/header.bqn b/test/cases/header.bqn
index 7c9d5a04..d43643ff 100644
--- a/test/cases/header.bqn
+++ b/test/cases/header.bqn
@@ -145,6 +145,7 @@
 2 % {𝕊a‿b:b-a}3‿5
 ! % {𝕊a‿b:𝕩}↕4
 2 % {A‿_b_:b-a}3‿5
+2 % 4{𝕨𝕊a‿b:𝕨-b÷a}3‿6
 ! % {a‿b:𝕩}↕4
 3 % {𝕊a‿B:b-a;≠𝕩}3‿5‿6
 1 % >´{⟨x⟩:1;𝕩:0}¨⟨2⟩‿6