error while calculating tiktok spend

marginal_cpc_calculator.py

@@ -72,6 +72,7 @@ def calculate_max_spend(df,min_date,max_date,
     df_temp['marginal_income'] = df_temp.cum_income - df_temp.cum_income.shift(1) - df_temp['marginal_cpc']
     
     try:
+        output_msg=[]
         params, cv = curve_fit(polynomial_func, df_temp['cum_cost'],df_temp['marginal_income'].fillna(0), p0=(1, 1,1,1))
         a,b,c,d = params
 
@@ -79,7 +80,7 @@ def calculate_max_spend(df,min_date,max_date,
         squaredDiffs = np.square(df_temp['marginal_income'].fillna(0) - polynomial_func(df_temp['cum_cost'], a,b,c,d))
         squaredDiffsFromMean = np.square(df_temp['marginal_income'].fillna(0) - np.mean(df_temp['marginal_income'].fillna(0)))
         rSquared = 1 - np.sum(squaredDiffs) / np.sum(squaredDiffsFromMean)
-        output_msg=[]
+
         if pprint==True:
             output_msg.append(f"R² of fit for marginal income = {rSquared}")
             # print(f"R² of fit for marginal income = {rSquared}")