better force eval ergonomic

fix-vm/src/instructions/calls.rs

@@ -1,6 +1,7 @@
 use fix_error::Error;
 use gc_arena::{Gc, Mutation, RefLock};
 
+use crate::value::*;
 use crate::{BytecodeReader, CallFrame, Closure, Env, Step, ThunkState, VmContextExt};
 
 impl<'gc> crate::Vm<'gc> {
@@ -11,12 +12,11 @@ impl<'gc> crate::Vm<'gc> {
         reader: &mut BytecodeReader<'_>,
         mc: &Mutation<'gc>,
     ) -> Step {
-        self.try_force(0, reader, mc)?;
+        let func = self.try_force::<StrictValue>(reader, mc)?;
         if self.call_depth > 10000 {
             return self.finish_err(Error::eval_error("stack overflow; max-call-depth exceeded"));
         }
         self.call_depth += 1;
-        let func = self.pop();
         let arg = reader.read_operand_data(ctx).resolve(mc, self);
         if let Some(closure) = func.as_gc::<Closure>() {
             let ip = closure.ip;