turtle/tlang: add else to if, fix end of scope error

clientmods/turtle/tlang.lua

@@ -157,7 +157,29 @@ local function test()
     1 2 test
     ]]
 
-    tlang.exec(repeat_test)
+    local ifelse_test = [[
+        {
+            {
+                'if' print
+            } {
+                'else' print
+            } if
+        } `ifprint =
+
+        1 ifprint
+        0 ifprint
+    ]]
+
+    local nest_run = [[
+        {
+            {
+                'innermost' print
+            } run
+        } run
+        'work' print
+    ]]
+
+    tlang.exec(ifelse_test)
 end
 
 if minetest == nil then

clientmods/turtle/tlang_vm.lua

@@ -190,6 +190,8 @@ local function getnext(state)
         if pc.sg == 0 then
             state.code_stack[pc.pos] = nil
         end
+
+        return getnext(state)
     end
 
     local current
@@ -355,6 +357,15 @@ tlang.builtins["if"] = function(state)
             tlang.push_raw(state, tos)
             tlang.call_tos(state)
         end
+    elseif tos1.type == "code" then
+        local tos2 = statepop_num(state)
+        if tos2.value ~= 0 then
+            tlang.push_raw(state, tos1)
+            tlang.call_tos(state)
+        else
+            tlang.push_raw(state, tos)
+            tlang.call_tos(state)
+        end
     end
 end