src/codegen/spirv/Assembler.zig: fix OpConstant

OpConstant with a floating point type argument fails to assemble with no
disagnostics provided as there's (what seems to be) a missing return.

Author: xor-shift

src/codegen/spirv/Assembler.zig

@@ -754,12 +754,12 @@ fn parseContextDependentNumber(ass: *Assembler) !void {
             const id = entry.value_ptr.*;
             if (id != result_id) continue;
             const info = entry.key_ptr.*;
-            switch (info.bits) {
+            return switch (info.bits) {
                 16 => try ass.parseContextDependentFloat(16),
                 32 => try ass.parseContextDependentFloat(32),
                 64 => try ass.parseContextDependentFloat(64),
                 else => return ass.fail(tok.start, "cannot parse {}-bit info literal", .{info.bits}),
-            }
+            };
         }
     }