Better handling of no ZDW found

src/dispersionapp/gui.py

@@ -23,12 +23,12 @@ def app(config_file: os.PathLike | None = None):
 
     with PlotApp(
         f"Dispersion design with {config.gas.title()}",
-        core_diameter_um=np.linspace(50, 300),
+        core_diameter_um=np.arange(50, 301, dtype=float),
         pressure_mbar=np.geomspace(1, 2000),
         wall_thickness_um=np.geomspace(0.01, 10),
         n_tubes=np.arange(6, 16),
-        gap_um=np.linspace(1, 15),
-        t_fwhm_fs=np.linspace(10, 200, 96),
+        gap_um=np.arange(1, 15.5, 0.5),
+        t_fwhm_fs=np.arange(10, 201, dtype=float),
     ) as app:
         # initial setup
         app[0].horizontal_line("reference", 0, color="gray")
@@ -64,7 +64,7 @@ def app(config_file: os.PathLike | None = None):
             disp = compute_capillary(core_diameter_um, pressure_mbar)
             wl_zero_disp = sc.math.all_zeros(wl, disp)
             if len(wl_zero_disp) == 0:
-                return
+                raise ValueError("No zero dispersion found")
             wl_zero_disp = wl_zero_disp[0]
 
             with warnings.catch_warnings():
@@ -138,15 +138,22 @@ def app(config_file: os.PathLike | None = None):
 
         @app.update
         def draw_energy_limit(core_diameter_um: float, pressure_mbar: float, t_fwhm_fs: float):
-            lim = compute_max_energy(core_diameter_um, pressure_mbar, t_fwhm_fs)
-            zdw = lim.wl_zero_disp * 1e9
-            app[0].set_line_data("zdw", [zdw, zdw], [-3, 3])
-
             info_lines = [
                 f"gas = {config.gas.title()}",
                 f"rep rate = {config.rep_rate*1e-3}kHz",
-                f"ZDW = {zdw:.0f}nm",
             ]
+
+            try:
+                lim = compute_max_energy(core_diameter_um, pressure_mbar, t_fwhm_fs)
+            except ValueError:
+                info_lines.append("No ZDW found")
+                app.info_label.setText("\n".join(info_lines))
+                return
+
+            zdw = lim.wl_zero_disp * 1e9
+            app[0].set_line_data("zdw", [zdw, zdw], [-3, 3])
+
+            info_lines.append(f"ZDW = {zdw:.0f}nm")
             if lim.ion_lim > lim.sf_lim:
                 power = lim.sf_lim * 1e3 * config.rep_rate
                 info_lines += [