refactor: catch payment and invoice error at faspi exceptionhandler level (#2484)

refactor exceptionhandlers into `exception.py` also now always throw
payment error when pay_invoice and invoice errors when create_invoice.

return a status flag with the detailed error message. with a 520
response

lnbits/exceptions.py

@@ -0,0 +1,101 @@
+import sys
+import traceback
+from http import HTTPStatus
+from typing import Optional
+
+from fastapi import FastAPI, HTTPException, Request
+from fastapi.exceptions import RequestValidationError
+from fastapi.responses import JSONResponse, RedirectResponse, Response
+from loguru import logger
+
+from lnbits.core.services import InvoiceError, PaymentError
+
+from .helpers import template_renderer
+
+
+def register_exception_handlers(app: FastAPI):
+    register_exception_handler(app)
+    register_request_validation_exception_handler(app)
+    register_http_exception_handler(app)
+    register_payment_error_handler(app)
+    register_invoice_error_handler(app)
+
+
+def render_html_error(request: Request, exc: Exception) -> Optional[Response]:
+    # Only the browser sends "text/html" request
+    # not fail proof, but everything else get's a JSON response
+    if (
+        request.headers
+        and "accept" in request.headers
+        and "text/html" in request.headers["accept"]
+    ):
+        if (
+            isinstance(exc, HTTPException)
+            and exc.headers
+            and "token-expired" in exc.headers
+        ):
+            response = RedirectResponse("/")
+            response.delete_cookie("cookie_access_token")
+            response.delete_cookie("is_lnbits_user_authorized")
+            response.set_cookie("is_access_token_expired", "true")
+            return response
+
+        return template_renderer().TemplateResponse(
+            request, "error.html", {"err": f"Error: {exc!s}"}
+        )
+
+    return None
+
+
+def register_exception_handler(app: FastAPI):
+    @app.exception_handler(Exception)
+    async def exception_handler(request: Request, exc: Exception):
+        etype, _, tb = sys.exc_info()
+        traceback.print_exception(etype, exc, tb)
+        logger.error(f"Exception: {exc!s}")
+        return render_html_error(request, exc) or JSONResponse(
+            status_code=HTTPStatus.INTERNAL_SERVER_ERROR,
+            content={"detail": str(exc)},
+        )
+
+
+def register_request_validation_exception_handler(app: FastAPI):
+    @app.exception_handler(RequestValidationError)
+    async def validation_exception_handler(
+        request: Request, exc: RequestValidationError
+    ):
+        logger.error(f"RequestValidationError: {exc!s}")
+        return render_html_error(request, exc) or JSONResponse(
+            status_code=HTTPStatus.BAD_REQUEST,
+            content={"detail": str(exc)},
+        )
+
+
+def register_http_exception_handler(app: FastAPI):
+    @app.exception_handler(HTTPException)
+    async def http_exception_handler(request: Request, exc: HTTPException):
+        logger.error(f"HTTPException {exc.status_code}: {exc.detail}")
+        return render_html_error(request, exc) or JSONResponse(
+            status_code=exc.status_code,
+            content={"detail": exc.detail},
+        )
+
+
+def register_payment_error_handler(app: FastAPI):
+    @app.exception_handler(PaymentError)
+    async def payment_error_handler(request: Request, exc: PaymentError):
+        logger.error(f"PaymentError: {exc.message}, {exc.status}")
+        return JSONResponse(
+            status_code=520,
+            content={"detail": exc.message, "status": exc.status},
+        )
+
+
+def register_invoice_error_handler(app: FastAPI):
+    @app.exception_handler(InvoiceError)
+    async def invoice_error_handler(request: Request, exc: InvoiceError):
+        logger.error(f"InvoiceError: {exc.message}, Status: {exc.status}")
+        return JSONResponse(
+            status_code=520,
+            content={"detail": exc.message, "status": exc.status},
+        )