Tips on using geom_contour_filled() - currently giving breaks related error

I am trying to create a contour plot. I have loaded a list of csv's into a combined_df. There are three columns - tau, time and gamma. Tau is the x axis, time is the y axis and gamma is what I want to give the intensity in the contour plot. Each 'time' is a particular csv. My current script is:

# Function to read and process a single CSV file
process_csv <- function(file_name, time_stamp) {
  # Read the CSV file, skipping the first three rows
  df <- read_csv(file_name, skip = 3)
  
  # Use the CSV name as a time stamp
  df$time <- time_stamp
  
  # Convert tau to log10 scale
  df$tau <- log10(df$tau)
  
  return(df)
}

# List of CSV files (assuming they are in your working directory)

filelist_grad = list.files(pattern = "*.csv")

csv_files <- stringr::str_sort(filelist_grad, numeric = TRUE)
csv_files

# Time stamps based on CSV file names
time_stamps <- seq(0.5, by = 0.5, length.out = length(csv_files))

# Process each CSV file and combine them into a single data frame
data_list <- mapply(process_csv, csv_files, time_stamps, SIMPLIFY = FALSE)
combined_df <- bind_rows(data_list)

# Interpolate data to a regular grid
d1 <- with(combined_df, interp(x = tau, y = time, z = gamma))

# Melt the z matrix to long format
d2 <- melt(d1$z, na.rm = TRUE)
names(d2) <- c("x", "y", "gamma")

# Add NMDS1 and NMDS2 from d1
d2$NMDS1 <- d1$x[d2$x]
d2$NMDS2 <- d1$y[d2$y]

# Create the plot
ggplot(data = d2, aes(x = NMDS1, y = NMDS2, z = gamma, group = cut_number(gamma, g=100))) +
  geom_contour_filled(bins = 20, breaks = seq(0, 120, by = 10)) +
  scale_fill_gradient(limits = c(0, 100), low = "yellow", high = "red") +
  theme_minimal()

This gives me this error: Error in geom_contour_filled(): ! Problem while computing aesthetics. i Error occurred in the 1st layer. Caused by error in breaks(): ! Specify exactly one of n and width.

I'm not really sure how to fix - any help is much appreciated!!I'm happy to forward on example data - my data is quite large and is quite hard to produce a reproducible example of which fits in the box!

Do you get the same error if you use n = 100 in your cut_number(), instead of g = 100, and use more breaks?

E.g. using the built-in ggplot2 dataset faithfuld:

library(tidyverse)

faithfuld %>%
  ggplot(aes(x = log10(waiting), y = eruptions, z = 100 * density,
             group = cut_number(density, n = 100))) +
  geom_contour_filled(bins = 20, breaks = seq(0, 120, by = 1))

^{Created on 2024-06-20 with reprex v2.1.0}