Buggy python submission (verdict: Runtime Error):
class UnionFind():
    def __init__(self, n):
        self.n = n
        self.root = [-1]*(n+1)
        self.rnk = [0]*(n+1)
        self.weight = [0]*(n+1)
 
    def Find_Root(self, x):
        if(self.root[x] < 0):
            return x
        else:
            self.root[x] = self.Find_Root(self.root[x])
            self.weight[x] += self.weight[self.root[x]]
            return self.root[x]

    def GetWeight(self, x):
      self.Find_Root(self, x)
      return self.weight[x]

    def Unite(self, x, y, w):
        w += self.GetWeight(x)
        w -= self.GetWeight(y)
        x = self.Find_Root(x)
        y = self.Find_Root(y)
        if(x == y):
            return False

        if self.rnk[x] < self.rnk[y]:
            x, y = y, x
            w = -w
        if self.rnk[x] == self.rnk[y]:
            self.rnk[x] += 1
        
        self.root[y] = x
        self.weight[y] = w

        return True
 
    def isSameGroup(self, x, y):
        return self.Find_Root(x) == self.Find_Root(y)
 
    def Count(self, x):
        return -self.root[self.Find_Root(x)]
    
    def Diff(self, x, y):
      if self.isSameGroup(x, y):
        return abs(self.GetWeight(y)- self.GetWeight(xs))
      else:
        return None

def main():
  N, M = map(int, input().split())
  lrd = [list(map(int, input().split())) for _ in range(M)]
  U = UnionFind(N)
  flag = True

  for i in range(M):
    l, r, d = lrd[i]
    U.Unite(l, r, d)
  for i in range(M):
    l, r, d = lrd[i]
    if U.isSameGroup(l, r):
      if U.Diff(l, r) != d:
        print('No')
        exit()
  print('Yes')
  
    
if __name__ == "__main__":
  main()

Fixed submission:
import sys
sys.setrecursionlimit(10**5)
class UnionFind():
    def __init__(self, n):
        self.n = n
        self.root = [-1]*(n+1)
        self.rnk = [0]*(n+1)
        self.weight = [0]*(n+1)
 
    def Find_Root(self, x):
        if(self.root[x] < 0):
            return x
        else:
            r = self.Find_Root(self.root[x])
            self.weight[x] += self.weight[self.root[x]]
            self.root[x] = r
            return r

    def GetWeight(self, x):
      self.Find_Root(x)
      return self.weight[x]

    def Unite(self, x, y, w):
        w += self.GetWeight(x)
        w -= self.GetWeight(y)
        x = self.Find_Root(x)
        y = self.Find_Root(y)
        if(x == y):
            return False

        if self.rnk[x] < self.rnk[y]:
            x, y = y, x
            w = -w
        if self.rnk[x] == self.rnk[y]:
            self.rnk[x] += 1
        
        self.root[y] = x
        self.weight[y] = w

        return True
 
    def isSameGroup(self, x, y):
        return self.Find_Root(x) == self.Find_Root(y)
 
    def Count(self, x):
        return -self.root[self.Find_Root(x)]
    
    def Diff(self, x, y):
        return self.GetWeight(y) - self.GetWeight(x)

def main():
  N, M = map(int, input().split())
  lrd = [list(map(int, input().split())) for _ in range(M)]
  U = UnionFind(N)
  for i in range(M):
    l, r, d = lrd[i]
    if not U.isSameGroup(l, r):
      U.Unite(l, r, d)
    else:
      if U.Diff(l, r) != d:
        print('No')
        exit()
  print('Yes')
  
    
if __name__ == "__main__":
  main()