Fix tools/emcoverage.py and EMSDK_PYTHON normalization

Resolve the minimal set of issues that prevented `tools/emcoverage.py`
from collecting coverage:

1. In `tools/emcoverage.py`, strip `-E` passed by compiler entry point
   scripts, and resolve commands to root `.py` files.
2. In `tools/config.py`, normalize `EMSDK_PYTHON` with `os.path.abspath()`
   instead of `sys.executable`, which prevented child processes from
   executing under custom wrappers.
3. In `tools/emcoverage.py`, pass `ignore_errors=True` to `rmtree` during
   reset.

Author: sbc100

tools/config.py

@@ -71,7 +71,7 @@ def normalize_relative_python_path():
   # reinitialize EMSDK_PYTHON here so that sub-tool spawns will use the same
   # Python interpreter as the parent.
   if os.environ.get('EMSDK_PYTHON'):
-    os.environ['EMSDK_PYTHON'] = sys.executable
+    os.environ['EMSDK_PYTHON'] = os.path.abspath(os.environ['EMSDK_PYTHON'])
 
 
 def set_config_from_tool_location(config_key, tool_binary, f):

tools/emcoverage.py

@@ -39,6 +39,7 @@
 import coverage.cmdline  # type: ignore
 
 SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
+ROOT_DIR = os.path.dirname(SCRIPT_DIR)
 
 
 def main():
@@ -56,7 +57,7 @@ def main():
     return
 
   if sys.argv[1] == 'reset':
-    shutil.rmtree(store)
+    shutil.rmtree(store, ignore_errors=True)
     return
 
   if sys.argv[1] in {'html', 'report', 'xml'}:
@@ -67,10 +68,18 @@ def main():
     sys.argv = [*old_argv, '-i']
     return coverage.cmdline.main()
 
-  if not os.path.exists(sys.argv[1]):
-    # If argv[1] is not a file path, instead try to interpret it as an emscripten command.
-    # This allows `emcoverage.py emcc` or `emcoverage.py embuilder` to work.
-    sys.argv[1] = os.path.join(os.path.dirname(sys.executable), '..', sys.argv[1] + '.py')
+  if sys.argv[1] == '-E':
+    sys.argv.pop(1)
+
+  # If argv[1] is an emscripten command rather than a python script path, resolve it
+  # to the corresponding root python script. This allows `emcoverage.py emcc` or
+  # `emcoverage.py embuilder` to work, even when launcher scripts (or binaries like
+  # `emcc.exe` on Windows) exist with the same name.
+  if not sys.argv[1].endswith('.py'):
+    cmd = os.path.basename(sys.argv[1]).removesuffix('.exe')
+    cmd_py = os.path.join(ROOT_DIR, cmd + '.py')
+    if os.path.exists(cmd_py):
+      sys.argv[1] = cmd_py
 
   try:
     os.mkdir(store)