show actual error when graphData fails

The original reason for the catch-all message was users with bad
data such as decimal intervals, but those get automatically coerced
these days. The common case should now be invalid search strings, which
we can show verbatim.

ftl/core/statistics.ftl

@@ -172,7 +172,6 @@ statistics-elapsed-time-years = { $amount }y
 
 ##
 
-statistics-error-fetching = Error searching - please check your search is correct, or use the Check Database feature.
 statistics-average-for-days-studied = Average for days studied
 statistics-total = Total
 statistics-days-studied = Days studied

qt/aqt/mediasrv.py

@@ -287,11 +287,14 @@ def handle_post(path: str) -> Response:
         return flask.make_response("Collection not open", HTTPStatus.NOT_FOUND)
 
     if path in post_handlers:
-        if data := post_handlers[path]():
-            response = flask.make_response(data)
-            response.headers["Content-Type"] = "application/binary"
-        else:
-            response = flask.make_response("", HTTPStatus.NO_CONTENT)
+        try:
+            if data := post_handlers[path]():
+                response = flask.make_response(data)
+                response.headers["Content-Type"] = "application/binary"
+            else:
+                response = flask.make_response("", HTTPStatus.NO_CONTENT)
+        except Exception as e:
+            return flask.make_response(str(e), HTTPStatus.INTERNAL_SERVER_ERROR)
     else:
         response = flask.make_response(
             f"Unhandled post to {path}",

ts/graphs/GraphsPage.svelte

@@ -37,7 +37,7 @@
             revlogRange = daysToRevlogRange(days);
         } catch (e) {
             sourceData = null;
-            alert(i18n.tr(i18n.TR.STATISTICS_ERROR_FETCHING));
+            alert(e);
         }
         active = false;
     };

ts/lib/postrequest.ts

@@ -7,7 +7,8 @@ export async function postRequest(path: string, body: string): Promise<Uint8Arra
         body,
     });
     if (!resp.ok) {
-        throw Error(`unexpected reply: ${resp.statusText}`);
+        const body = await resp.text();
+        throw Error(`${resp.status}: ${body}`);
     }
     // get returned bytes
     const respBlob = await resp.blob();