fix: improve error handling and type safety

- Replaced 'any' types with proper TypeScript types
- Improved error handling with instanceof checks
- Removed unused imports (calculateExpectedTeamScore)
- Updated error messages to be more descriptive
- Removed deprecated eslint.config.mjs file

src/app/api/matches/upload/route.ts

@@ -3,7 +3,7 @@ import { prisma } from "@/lib/prisma";
 import Papa from "papaparse";
 import { canManageTournament } from "@/lib/permissions";
 import { getSession } from "@/lib/auth-simple";
-import { calculateTeamElo, calculateExpectedTeamScore, calculateTeamEloChange } from "@/lib/elo-utils";
+import { calculateTeamElo, calculateTeamEloChange } from "@/lib/elo-utils";
 
 interface CSVRow {
   "Event #": string;
@@ -62,7 +62,7 @@ export async function POST(request: Request) {
 
     if (parseResult.errors.length > 0) {
       return NextResponse.json(
-        { error: "CSV parsing errors", errors: parseResult.errors.map((e: any) => e.message) },
+        { error: "CSV parsing errors", errors: parseResult.errors.map((e: { message: string }) => e.message) },
         { status: 400 }
       );
     }
@@ -164,15 +164,16 @@ export async function POST(request: Request) {
                 registrationDate: new Date(),
               },
             });
-          } catch (error) {
+          } catch {
             // Participant already exists, which is fine
             console.log(`Participant ${player.id} already exists in tournament ${eventId}`);
           }
         }
 
         importedCount++;
-      } catch (err: any) {
-        errors.push(`Row ${index + 2}: ${err.message}`);
+      } catch (err: unknown) {
+        const message = err instanceof Error ? err.message : "Unknown error";
+        errors.push(`Row ${index + 2}: ${message}`);
         errorCount++;
       }
     }
@@ -182,10 +183,11 @@ export async function POST(request: Request) {
       errorCount,
       errors: errors.length > 0 ? errors : undefined,
     });
-  } catch (error: any) {
+  } catch (error: unknown) {
     console.error("Upload error:", error);
+    const message = error instanceof Error ? error.message : "Failed to upload CSV";
     return NextResponse.json(
-      { error: error.message || "Failed to upload CSV" },
+      { error: message },
       { status: 500 }
     );
   }