Inspect producing weird errors and does not show graph

When using inspect it does not show the graph.
It is the first time I used it on a vanilla install (latest VScode and PIO on Linux Mint), and after looking closer at clang-tidy.
So this threat separates this topic of “inspect not showing a graph” from the tidy thread Clang-tidy: what is the proper set-up? - #5 by maxg

maxgerhardt already mentioned:

The longish output is here: pio check -v - Pastebin.com

Any hints appreciated.

I was trying to reproduce this in some environments and configurations with a pretty empty code, but it was working okay.

[env]
framework = arduino
check_tool = clangtidy

[env:uno]
platform = atmelavr
board = uno

[env:stm32]
platform = ststm32
board = nucleo_l476rg
check_skip_packages = yes

with src/main.cpp as

#include <Arduino.h>

void setup() {
    Serial.begin(9600);
}

void loop() {
    Serial.println("Hello");
    delay(1000);
}

the pio check could be executed successfully. Can you give an example project where it fails?