beamcenterfit.py: return None instead of exit()

src/aare/daq/beamcenterfit.py

@@ -64,9 +64,9 @@ def beamcenter_fit(image:np.ndarray) -> Gaussian2Dfit:
     roi_flat = roi.ravel()
     try:
         popt, _ = curve_fit(gaussian_2d, xy, roi_flat, p0=initial_guess)
-    except RuntimeError:
-        print("Error: Gaussian fitting did not converge.")
-        exit()
+    except RuntimeError as e:
+        print(f"Error: Gaussian fitting did not converge: {e}")
+        return None
 
     # Extract fitted parameters
     x0, y0, sigma_x, sigma_y, ini_theta, intensity, _ = popt