问为什么我的残差的正常Q-Q图是一条垂直线？

EN

from matplotlib.pyplot import subplot_mosaic, show, rc
from matplotlib.lines import Line2D
from matplotlib.transforms import blended_transform_factory
from numpy.random import default_rng
from numpy import linspace
from sklearn.linear_model import LinearRegression
from statsmodels.api import qqplot
from scipy.stats import zscore

rc('font', size=14)
rc('axes.spines', top=False, right=False)

rng = default_rng(0)
size = 100

x_values = linspace(0, 5, size)[:, None]
errors = {
    'uniform': rng.uniform(low=-50, high=50, size=(size, 1)),
    'normal':  rng.normal(loc=0, scale=15, size=(size, 1))
}

fig, axd = subplot_mosaic([
    ['uniform_fit', 'uniform_hist', 'uniform_qq_bad', 'uniform_qq_good'],
    ['normal_fit', 'normal_hist', 'normal_qq_bad', 'normal_qq_good']
], figsize=(12, 6), gridspec_kw={'wspace': .4, 'hspace': .2})

for err_type, err in errors.items():
    reg = LinearRegression()
    y_values = 29 * x_values + 30 + err

    fit = reg.fit(x_values, y_values)
    predictions = fit.predict(x_values)
    residuals = predictions - y_values

    axd[f'{err_type}_fit'].scatter(x_values, y_values, s=10, alpha=.8)
    axd[f'{err_type}_fit'].plot(x_values, predictions)

    axd[f'{err_type}_hist'].hist(residuals, bins=20)

    qqplot(residuals, ax=axd[f'{err_type}_qq_bad'], line='q')
    qqplot(residuals[:, 0], ax=axd[f'{err_type}_qq_good'], line='q')

####
# Below is primarily for plot aesthetics, feel free to ignore

for label, ax in axd.items():
    ax.set_ylabel(None)
    ax.set_xlabel(None)

    if label.startswith('uniform'):
        ax.set_title(label.replace('uniform_', '').replace('_', ' '))

    if label.endswith('fit'):
        ax.set_ylabel(f'{label.replace("_fit", "")} error')

line = Line2D(
    [.05, .95], [1.04, 1.04],
    color='black',
    transform=blended_transform_factory(fig.transFigure, ax.transAxes),
)
fig.add_artist(line)

show()