Fix parsing of INT_MIN %arg

Fixes #4601

src/command_manager.cc

@@ -382,10 +382,10 @@ void expand_token(Token&& token, const Context& context, const ShellContext& she
                 return set_target(params);
         }
 
-        const int arg = str_to_int(content)-1;
+        const int arg = str_to_int(content);
-        if (arg < 0)
+        if (arg < 1)
             throw runtime_error("invalid argument index");
-        return set_target(arg < params.size() ? params[arg] : String{});
+        return set_target(arg <= params.size() ? params[arg-1] : String{});
     }
     case Token::Type::FileExpand:
         return set_target(read_file(content));

test/regression/4601-int-min-arg/cmd

@@ -0,0 +1 @@
+

test/regression/4601-int-min-arg/in

@@ -0,0 +1 @@
+

test/regression/4601-int-min-arg/out

@@ -0,0 +1 @@
+ok

test/regression/4601-int-min-arg/rc

@@ -0,0 +1,5 @@
+try %{
+    nop %arg{-2147483648}
+} catch %{
+    exec iok<esc>
+}